Shitting myself about going back to work

I've just handed a grievance letter to my work stating details of workplace bullying and discrimination against me by the CEO, my line manager.I'm currently off work on stress leave after having panic attacks at work due to his behaviour but plan to return next Monday. It's a small office, just 5 of us, and I am absolutely terrified about going back to work even though I know I am totally in the right and have tons of evidence to back up my case.

Anyone have experience of a similar situation? I actually really like my job but the CEO is a monster so I just want to stay there to get another maternity leave next year out of it and then find something else.